The present invention relates to tracked vehicles and in particular relates to tracks for skid steer vehicles.
Skids steer vehicles are commonly encountered in the construction, landscape, agricultural, or lumber industries. Typically, skid steer vehicles have a pair of in-line tires on each side of the vehicle. To advance, both pairs of the tires are rotated in the same direction; to turn the skid steer vehicle, the tires on one side of the vehicle are rotated in opposition to tires on the opposite side. While such vehicles are quite useful, under some conditions, the tires lack adequate traction with the ground. That is, in mud or upon ice, one or more of these tires lose traction with the ground and dig into the ground or slide sideways. Such performance is unacceptable under work conditions and may even be dangerous. Providing tracks has been an oft considered and sometimes employed alternative.
The available track systems for skid steer vehicles, however, also have some considerable drawbacks. One such system is an entirely rubber track. Rubber tracks are extremely expensive and not particularly durable. Another such system is a xe2x80x9cgrouserxe2x80x9d type track. Grouser tracks may be described as plates, with a short connector on either side of the plate, used to provide a track for the tires of the skid steer. The two short links of the grouser track are not in the plane traveled by the tires but rather displaced upward from the plane traveled by the tires. As such, they generate what might be described as a pair of hinge points on each side of the plates in the grouser type track. The distortion resulting from four hinge points allows considerable and undesirable flexibility between adjacent grouser plates. Again, the grouser track suffers from a high price and limited durability. Both forms of tracks also suffer from a performance issue in which the track twists when not directly in contact with a tire. When traversing over a rock or stump or similar obstacle, the track particularly twists in the ground contact segment between the tires and the skid steer vehicle slides unexpectedly sideways.
It would be highly desirable to provide a less expensive track with better performance characteristics than those currently available from rubber tracks or grouser style tracks.
In an effort to address the expense and undesirable performance characteristics available from rubber or grouser type tracks, this inventor happened upon the serendipitous discovery that existing commercial chains, in extensive use in alternative industries might be modified and adapted for use as skid steer tracks. In particular, this inventor observed that certain chains, known as drag chains, commonly employed to move bulk materials through conveyors in sawmills, pulp and paper mills and similar industries might be employed, with inventive modifications, as tracks for skid steer vehicles. Such chains typically are pulled by a power sprocket adjacent a discharge of a conveyor. An idler sprocket at the beginning of the conveyor trough typically serves to maintain the drag chain in a desired position with the end of the trough. In conveyor use, side adapters are also often employed to maintain the drag chain in the desired position within the trough. Many, but not all, of the attributes desired for a skid steer vehicle track are present in such drag chains. Notably, such chains are relatively durable, having been developed for continuous use dragging bulk materials through a trough to move materials in a specific direction. Further, the chains are produced in substantial quantity, rather than being a high-priced specialty item. Thus, the basic chain, without the tire side guides and modifications of this invention is relatively inexpensive, Moreover, the single hinge formed between each link of a drag chain extends from one side to the other, rather than being two separate smaller hinges on each side of a grouser plate, and therefore would, in theory, allow less xe2x80x9ctwistxe2x80x9d than a grouser style track or a rubber track.
In a first embodiment, a track for a skid steer vehicle according to the present invention, includes a plurality of links. Each link has a pin, a first and second sidebar extending radially from the pin, and a barrel attached to the opposite ends of the sidebars. The sidebars also include an inset-jog which narrows the space in-between the sidebars to correspond to the shorter barrel length. The barrel is rigidly attached to the sidebars. The pin is also radially locked with respect to the side bars. Assembled as a chain, the pin is captured or encased within the barrel. The pin and barrel together form a hinge between sequential links. Moreover, the hinge defines a tire support surface for a tire of the skid steer vehicle on a first side and a ground engaging support on the second side. Projecting from the sidebars, on the first side, are a pair of tire side guides. The tire side guides defined the edges or lateral boundaries of a guided pathway for the tire of the skid steer vehicle over the tire support of the barrel-pin hinge. Preferably, at least the basic chain (i.e. sidebars, barrel and pin) is formed of hardened steel, for example, heat tempered steel.
In some situations, the ends of the chain may be joined to one another and form a perfect fit, or near perfect fit, for a pair of in-line tire of a skid steer vehicle. This is due to the appropriate track length equaling a multiple of links. In other situations, a spacer link must be employed. In one embodiment of the present invention, the spacer link may be a separable bar with a pin end and a barrel end. The two separable parts of the spacer bars may be joined by a bolt and nut arrangement. In another embodiment of the present invention, the spacer link may include a plurality of apertures or holes so that the correct spacing may be selected from amongst the plurality of apertures. Most preferably, the connector system to close the loop has a short portion of bar at the the barrel and the pin, each of the bars have an aperature, and a connector segments with apertures are used to connect the two bars. A spacer is used to correct for a difference in lateral offset between the pin and barrel. If a plurality of connector segments are available with different lengths, wear can be accommodated.
In another embodiment of the present invention, a plurality of tire sizes may be accommodated by a single chain. This is due to the alternative spacings between the sidebar carried tire side guides provided by the offset-jog. That is, tire side guides carried adjacent to the barrel will be spaced to accommodate relatively narrow tires. Tire side guides carried adjacent the pin will be spaced to accommodate relatively wide tires. Tire side guides carried at the offset-jog will accommodate intermediate width tires.
In still another embodiment of the present invention, a plurality of tire sizes may be accommodated by a single modified chain in an interchangeable manner, by providing a plurality of attachment points at the earlier identified positions along the side bars. This interchangeability is achieved in combination with removable or separable tire side guides which can be interchangeably attached to a selected one of such positions. Preferably, such tire side guides are bolted for attachment to the side bars at desired positions. Most preferably, the attachment system further includes a means for preventing rotation about the attachment bolts. For example, a second bolt might be provided, an interacting flange, either above or below the side bar, or a supplemental pin arrangement.
In yet another embodiment of the present invention, a plurality of tire sizes maybe accommodated by providing tire side guides, with a relatively wide spacing, in combination with a tire side spacer. Alternatively, a variety of tire side spacers may be employed on one or both of the tire side guides to provide many optional tire width spacings.
In still another embodiment of the present invention, attachments for ground interacting or ground engaging accessories maybe provided on the links. In such a manner, a variety of the ground engaging accessories may be removably attached. Preferably, such ground engaging accessories are attached to the side bars. In one variation, where the sidebars carry a plurality of attachment apertures for moveable tire side guides, an un-occupied aperture may be used to attach the accessory. Alternatively, the ground engaging accessories in may be reversibly attached to the hinge, formed from the pin and barrel combination. Depending upon whether the exterior of the hinge moves with either the current link or the adjacent link, the accessory may be engaging the ground in a leading or following manner. In contrast, accessories carried on the side bar are always engaged with the remainder of the link. Alternatively, a dedicated attachment point may be provided for ground engaging accessories. If so, it is preferred that the dedicated attachment for accessories be a vertically oriented aperture (relative to the hinge axis.)
In other embodiments of the current invention, the present invention is a method of converting to a convertible chain by the steps of: providing a chain formed of links according to the appropriable descriptions and altering the spacing between the tire side guides (or tire side guides which spacers) and the center line as defined by mid points of the hinge formed by the barrel and pin combination of two adjoining links.